Ch 25 Vectorborne Diseases Flashcards
The liquid part of blood =
Serum
Erythrocytes, Leukocytes, & Platelets are all-
Formed Elements
This system carries excess fluids to the bloodstream and filters pathogens from the blood =
Lymphatic System
Any microbial infection of the blood that produces illness =
Septicemia
Presence of bacteria in the blood =
Bacteremia
Release of bacterial toxins into the blood =
Toxemia
Viruses in the blood =
Viremia
Fungi, generally yeast, in the blood =
Fungemia
Infection and inflammation of the lymphatic vessels =
Lymphangitis
Blood is usually -
Germ-Free (Axenic)
What are the signs and symptoms of Septicemia, Bacteremia, & Toxemia?
Fever, chills, nausea, vomiting, diarrhea, and malaise
Septic shock can develop rapidly
Small hemorrhagic lesions called Petechiae can develop
Osteomyelitis occurs if bacteria invade the bones
Inflammation/swelling of bone =
Osteomyelitis
Toxemia symptoms vary depending on-
The toxin itself
Toxins released from living microorganisms =
Exotoxins
Toxins released from Gram-negative bacteria (Lipid A) =
Endotoxins
What are the signs and symptoms of Lyme Disease?
Bull’s-eye rash at infection site
Neurological symptoms & cardiac dysfunction
Severe arthritis
How many phases does untreated Lyme Disease have?
Three
What are the signs and symptoms of the first phase of Lyme Disease?
Bull’s-eye rash at infection site:
Occurs in ~80% of people and lasts several weeks
Takes about 7 days to develop
Other early symptoms: malaise, headaches, dizziness, muscle and joint pain, infected
lymph nodes
What are the signs and symptoms of the second phase of Lyme Disease?
Neurological symptoms (Encephalitis & Meningitis) + cardiac disfunction:
If untreated occurs days to weeks later
Seen only in ~10% of patients
What are the signs and symptoms of the third phase of Lyme Disease?
Severe Arthritis:
~80% of patients
Occurs years later
Usually due to the immune response as bacteria have been cleared by this point
Is Lyme Disease fatal?
Rarely
Ticks have to remain on a host for how long to transmit enough Spirochetes to cause infection?
36-48 hrs
How do Spirochetes cause Lyme Disease?
They don’t do anything, but the body still sees it as a foreign invader so it does everything in it’s power to remove it (Thus causing Lyme’s Disease)
One of the most reported vector-borne diseases in the United States (Over 34,000 cases in 2015) =
Lyme Disease
Deer ticks are the cause of -
Lyme Disease
How is Lyme Disease diagnosed?
Diagnosis is based on the signs and symptoms of the disease
Bacterium is rarely detected in the blood
Antibody tests can be performed early in infection
How is Lyme Disease treated?
Antimicrobial drugs are used in the early phases
Treatment of later phases is difficult
How can Lyme Disease be prevented?
Prevented with tick repellents and protective clothing
Checking for ticks after outdoor activities
Swift removal via mouth parts, not squishing main body
What are the signs and symptoms of Rocky Mountain Spotted Fever?
Initial symptoms: High fever, headache, body aches, nausea, vomiting.
About 2-6 days after other symptoms develop, a rash begins at hands and wrists and spreads to trunk, face and extremities.
What does a rash caused by Rocky Mountain Spotted Fever indicate?
Severe infection. Without treatment, RMSF is fatal within 8 days of showing symptoms
Pt’s with RMSF usually die from-
Low BP or Cardiac Arrest
How long does a Rocky Mountain Wood Tick need to feed before it can cause RMSF?
Minimum of 6 hrs
RMSF is an endemic to-
North & South America
People most at risk for RMSF:
People who enjoy outdoor activities like hiking or hunting; people with jobs that are outdoors
How can you diagnose RMSF?
Can be difficult, RMSF mimics other diseases (Initial symptoms usually similar to gastrointestinal illness)
Patient history (outdoor activities, tick bite); symptoms and rash can be diagnostic
Tests like PCR from blood samples, tests for bacteria from biopsy samples from the rash
How can you treat RMSF?
Antibiotics
How can you prevent RMSF?
Wearing long clothes, tick repellent when outdoors especially during spring and summer; checking for ticks and showering shortly after being outdoors; making sure pets are treated for ticks
No vaccine available
What are the signs and symptoms of Gas Gangrene?
Increased pain and swelling around injury due to damage to blood vessels
Tissue begins to lack oxygen and starts to die
Creates an anaerobic environment suitable for the growth of anaerobic bacteria
What do the signs and symptoms of Gas Gangrene result in?
Fever, foul-smelling drainage from tissues
Crepitation (crackly sound due to gas collecting under skin)
Tissue becomes liquified and begins sloughing off
Enters through dead tissue via traumatic event like surgical incision or wound =
Gas Gangrene
How long does Gas Gangrene generally take to develop?
1 to 3 days
How can you treat Gas Gangrene?
Dead tissue must be surgically removed.
Antibiotics to kill bacteria and antitoxin to neutralize the toxins produced.
Can also be treated using hyperbaric chamber.
Gas Gangrene is a-
Medical Emergency
How does a Hyperbaric Chamber treat Gas Gangrene?
Chamber uses higher pressure of oxygen than normal air pressure to force oxygen into areas of necrosing tissue
where gas is collecting. This can kill the anaerobic pathogens that can’t tolerate oxygen
What are early symptoms of Ebola?
Headache, fever, fatigue, dizziness, sore throat, muscle pain followed by rash
Appear 2-21 days after infection
What’re symptoms of the middle stage of Ebola?
High fever, massive bloody vomiting, diarrhea
What are late symptoms of Ebola?
Damage to blood vessels causes severe internal hemorrhaging(escape of blood from a ruptured vessel)
Bleeding from orifices, eyes, nose, ears
Organ damage
Many survivors have life-long complications like joint pain and vision changes
What does Ebola bind to? Why?
It binds to Neutrophils to inhibit early immune response
It binds to cells in blood vessels facilitating viral entry and destroying the cells = Hemorrhaging
How is Ebola transmitted?
- Ebolavirus circulates in rural environments between bats, the natural reservoir.
- Can be transmitted to other animals that people use for food.
- Preparing these animals for consumption can result in spillover event in which Ebola is transmitted through contact with contaminated animal fluids (blood).
- Human becomes infected, transmitting to other humans who care for the infected individual.
Is Ebola an acute or chronic disease?
Acute
Ebola is fatal in what percent of pt’s?
50-90%
How can you diagnose Ebola?
Diagnosis is based on characteristic symptoms and presence of virus in the blood
Usually PCR is used to detect virus
Virus reaches detectable levels in blood after 3 days of symptoms
How can you treat Ebola?
F&E Replacement
How can you prevent yourself from getting Ebola?
There are no effective antiviral drugs that treat all types of Ebola
2 antivirals treat one type of Ebola
Vaccines are available to protect against future outbreaks
What are the immune cells HIV primarily targets?
Helper T Cells
How is HIV transmitted?
Via exchanges of bodily fluids (Unprotected sex or contaminated needles)
Why is it so hard to cure HIV?
HIV is in a place where meds can’t reach (Inside the DNA of Helper T Cells)
When does HIV become AIDS?
Whenever Helper T Cell counts get too low, the immune system can’t fight off deadly bacteria that it would normally be able to anymore. This is when HIV becomes AIDS
What does HIV stand for?
Human immunodeficiency virus
What does AIDS stand for?
acquired immune deficiency syndrome
What are the most infective bodily fluids for HIV?
Blood and semen are more infective than other secretions
Can HIV be transmitted from a mother to the baby during pregnancy, birth, or breastfeeding?
Yes
What are the 3 stages of HIV called?
Stage 1 = Primary Infection
Stage 2 = Clinical Latency
Stage 3 = AIDS
Helper T Cells are also called -
CD4+ Cells
What occurs during the first stage of HIV?
Virus replicates and is released from infected cells into the blood
Fever, fatigue, weight loss, diarrhea, body aches which lasts 2-4 weeks as antibodies are made to fight off infection
During this time, cytotoxic T cells kill 100 million virally infected CD4+ helper T cells but levels are above 500 cells/uL of blood
Patient’s are often unaware of HIV infection at this point as symptoms resemble the flu/other illnesses =
The Primary Infection Stage
What occurs during the second stage of HIV?
Over 5-10 years, virus enters period of dormancy
Number of helper T cells declines to a level that severely impairs the immune response (between 200 and 499 cells/uL of blood)
What occurs during the third stage of HIV?
Helper T cell levels are less than 200 cells/uL of blood, virus production climbs as there are no antibodies being made to fight it off
Patient has chills, swollen lymph nodes, weight loss, fatigue
Patient can experience a variety of opportunistic infections
Death usually results from opportunistic infection
How do you diagnose HIV/AIDS?
AIDS diagnosis is based on symptoms, low levels of CD4+ lymphocytes, and presence of antibodies against HIV
Antibodies against HIV are detected by ELISA or western blot
Positive test for HIV antibodies does not automatically indicate presence of AIDS
How is HIV treated?
Antiretroviral Therapy (ART) currently used to reduce viral replication:
ART is a cocktail of antiviral drugs, like reverse transcriptase inhibitors and integrase inhibitors
Does not cure the infection
Inhibits HIV replication
Patient can live relatively normal life while on treatment
Is there a vaccine for HIV/AIDS?
No
How can you prevent AIDS?
Behavioral changes can slow the AIDS epidemic
Pre-exposure prophylaxis (oral tenofovir)
(Truvada)
What behavioral changes can prevent AIDS?
Abstinence and safe sex
Use of clean needles
Providing antiviral drugs to infected pregnant women
Screening of blood products
Use of protective wear to prevent contact with blood
How does Pre-exposure prophylaxis (oral tenofovir) (Truvada) prevent HIV/AIDS?
Pill taken daily can prevent HIV from sex by 99%
For those who inject drugs PrEP reduces HIV infection by 74% when taken daily
Vaginal application of tenofovir before and after intercourse reduces the chance of infection
What is Infectious Mononucleosis?
Syndrome that can be caused by a variety of different pathogens
What are the usual signs and symptoms of Infectious Mononucleosis?
Fever
10% atypical (large cytoplasm) lymphocytes in blood
What is Infectious Mononucleosis?
Commonly known as the kissing disease or Mono
Condition resulting from interactions of a patient’s cellular immune system with infected B lymphocytes
What are the signs and symptoms of Infectious Mononucleosis?
Incubation time of 4-7 weeks
Severe sore throat and fever occur initially
Followed by swollen lymph nodes, enlarged spleen, fatigue, appetite loss, and a skin rash
Fatigue and inability to concentrate may last for months
The Epstein-Barr Virus (EBV or HHV-4) is the causative agent of-
Infectious Mononucleosis
What does EBV do?
Suppresses apoptosis of infected B cells
How does transmission of Infectious Mononucleosis occur?
Via saliva, blood, and semen
95% of adults worldwide have been infected with Infectious Mononucleosis by the age of-
6
How is Infectious Mononucleosis diagnosed?
Diagnosed by presence of large, lobed B lymphocytes and neutropenia (few neutrophils in the blood)
How is Infectious Mononucleosis treated?
Treatment focuses on relieving symptoms
How is Infectious Mononucleosis prevented?
Prevention is difficult since EBV occurrence is widespread
Cytomegalovirus infections =
Human Herpesvirus 5
What percentage of people have been infected by Cytomegalovirus by adulthood?
50%
What does Cytomegalovirus infect?
Infects epithelial cells, macrophages and lymphocytes
How is Cytomegalovirus transmitted?
Transmitted sexually, via blood, urine, saliva, in breastmilk or by transplanted tissue
What are the manifestations of Cytomegalovirus?
May be asymptomatic or mild in adults
Infected cells swell forming “owl’s eyes” inclusions
How is Cytomegalovirus transmitted?
Transmitted across the placenta; causes mental retardation or hearing loss in newborns
Most people with Cytomegalovirus are asymptomatic and don’t require treatment
True or false?
True
How is Cytomegalovirus diagnosed?
The “C” in “TORCH” prenatal screenings
How are Cytomegalovirus’ treated?
Various antivirals are available for those with overt symptoms (like newborns)
What are the signs and symptoms of Malaria?
Associated with parasite’s life in red blood cells, so symptoms are cyclical as parasites emerge from red blood cells
Fever, chills, diarrhea, and headache for a few hours
Profuse sweating, weakness, fatigue for a few hours
Anemia, weakness, jaundice and fatigue gradually occur
These are generally nonmotile, protozoal parasites transmitted by mosquitos =
Plasmodium
At least four Plasmodium species cause -
Malaria
What occurs whenever you have Malaria?
A mosquito transmits the parasite to the blood
The parasite travels to the liver and replicates
After 2 weeks the liver cells rupture releasing more parasites that go on to infect red blood cells
Periodically, parasites lyse red blood cells and enter blood, infecting more red blood cells
Results in liver damage, jaundice, anemia
Damage to red blood cells can lead to ‘sludge blood’ in which blood is thickened by lysed red blood cells
What does Sludge Blood prevent?
Prevents necessary oxygen delivery to organs = organ failure and death
How does Maria transmission occur?
Human to human transmission does not occur, but mosquitos can pick up parasites from humans that can complete development and infect other humans
Maria is an endemic throughout-
Tropics + Subtropics
Can anyone get Malaria?
Yes, but children are especially vulnerable
How is Malaria diagnosed?
Diagnosis made by identifying Plasmodium in blood using staining/microscopy
How is Malaria treated?
Treated with various antimalarial drugs
Some Plasmodium strains are resistant to antimalarial drugs
How is Malaria prevented?
Prevention requires control of mosquitoes
Use of mosquito nets is important way to reduce contact
No effective vaccine available
Chagas Disease is also called-
American Trypanosomiasis
What is Chagas Disease caused by?
Trypanosoma cruzi
The vector of Chagas Disease is-
The Reduviid Drug (Kissing Bug)
How is Chagas Disease caused by the kissing bug?
It defecates trypanosomes into the bite wound of humans
How is Chagas Disease treated?
Therapy is difficult due to trypanosome multiplying intracellularly
Antiprotozoal drugs can be helpful during early stage
Most patients show no early symptoms, and late stages of the disease cannot be
treated
How is Chagas Disease diagnosed?
Diagnosed by microscopic identification of T. cruzi
How is Chagas Disease prevented?
Prevention involves avoidance of the vector
How many stages are there of Chagas Disease?
3
What happens during Acute Infection of Chagas Disease?
Fever, vomiting, rash, diarrhea, etc.
What happens during the intermediate phase of Chagas Disease?
Asymptomatic
What happens during the chronic form of Chagas Disease?
Chronic form of the disease develops in ~20% of people infected
Swelling of colon, esophagus, heart
~23% of the human population has been infected with this by age 12 =
Taxopasmosis
What can cause someone to get Taxoplasmosis?
Contact with cat feces or undercooked meat introduces oocysts to the intestines
Oocysts form trophozoites that invade cells
Taxoplasmosis can become-
Chronic
What’s the primary danger with Taxoplasmosis?
Primary danger is congenital infection:
Stillbirth
Neurological damage
This virus causes about 90% of infectious mononucleosis cases. It is typically not associated with crossing the placenta or causing congenital issues =
The Epstein Barr Virus
This pathogen takes advantage of any anaerobic environment (Important to keep in mind for Gas Gangrene) =
Clostridium perfringens
